With an overwhelming number of face-cleansing products on the market and often-conflicting advice coming from all quarters, it's little wonder that many clients are confused and are doing unnecessary harm to their skin. The board-certified physicians of New York-based Advanced Dermatology and the Center for Laser and Cosmetic Surgery highlight mistakes and fallacies and cut through the clutter with guidelines for face-cleansing that restore simplicity and common sense.

"The most common mistake people make is to overdo it," says Meryl Blecker Joerg, MD. "Facial cleansing is important because the face has so many sebaceous glands that secrete oil. In addition, we apply cosmetics and products that create a film on the skin, trapping pollutants from the environment. But in our zeal to remove the day's accumulation of oil, sweat, dirt, bacteria, and dead skin cells, we tend to over-wash, over-scrub and over-dry our faces. Before scrubbing away all that oil and grime, people need to understand how delicate the skin on the face is. I recommend washes with salicylic acid in them rather than scrubs because scrubs can break up acne and cause scarring."

The outer layer of the epidermis, the stratum corneum, which is responsible for the barrier qualities of the skin, has fewer layers on the face than most other parts of the body, making facial skin thinner and more easily damaged. Also, the stratum corneum houses a layer of lipids, or fats, that make the skin soft and supple and play a major protective role. Scrubbing should never be so vigorous that it removes these barriers that protect the skin. "And cleaning your face should never, ever be painful," Joerg emphasizes. "A kinder, gentler approach will reduce irritation, dryness and flakiness."

Valerie Goldburt, MD, points out the other major face-cleansing mistake people make: using the wrong product. "The most frequent error is being overly aggressive, using a product that is too harsh for facial skin or for an individual's skin type," says Goldburt. "Some doctors advise against ever using soap on the face, but the most important thing to remember is to never use a product on the face - bar soap, gel or liquid cleanser - that is intended for use on the body."

Although facial and body cleansers have many ingredients in common, there are significant differences, particularly in the type of surfactant they contain. A surfactant (short for "surface-active agent") is a chemical added to many products that contains oil and water to keep the two famously nonmixing substances from separating. Facial cleansers are gentler on the skin because the surfactant they contain is milder than that of body cleansers. This difference in formulation explains why products for the face cost more than those for the body: milder surfactants are more expensive.

Helping clients choose a product: A general rule of thumb is to use a mild, moisturizing cleanser that removes oil and residue without leaving your skin dry, tight or flaky.

Do not use anything that contains deodorant, fragrance or antiseptic.

If you prefer a bar, only use one that is formulated for the face; these may be labeled beauty bars, facial soap, mild cleansing bars or sensitive skin bars.

Foaming facial cleansers work up a lather, are rinsed off and generally leave the face refreshed; they come as lotions, gels, creams and aerosols.

Nonfoaming cleansers are the mildest available because they use very little surfactant and are wiped off rather than rinsed; they come as cream, lotion, milk and the perennial cold cream, which dates to a time when the only alternative was harsh soap, but is now generally felt to be too greasy for all but the driest skin.

Scrubs and other exfoliating or buffing agents smooth the skin by removing dead skin cells, but most are too harsh and may cause redness and irritation. They should not be used on sensitive skin or more than once a week by anyone.

Toners and astringents are intended for use after cleansing to remove the last traces of makeup but they are unnecessary and often remove the natural oils that should remain on the skin.

Showing clients how to cleanse:

Clean your face twice daily if you have oily or normal skin, once a day if your skin is dry or damaged.

Use warm water; too hot or too cold will dry the skin and may cause flaking and itching.